Newer design available: Universal Auto-Rewind Spool Holder!
Filament load/unload issues? MMU2 taking too much space? Not with this Parametric Auto-Rewind spool holder! It keeps filament on the spool during unloading, up to eight full revolutions.
This is a remake of the original Auto-Rewind Spool Holder, but with significant enhancements:
- Fully parametric
- Default spring size 100mm gives up to eight rewinding revolutions
- Metal bearings can be used, but also works fine without any bearings
- No tape or zip-ties needed
- Compatible with existing spool stands with 8mm axle slots
- Spring blades in the hub keep the spool pressed against the backplate for adequate friction and prevention of spool sliding off the hub
- Adapter allows to mount differently-sized spools on the same hub
- Spacers included to keep hub in place
- Spring guard included
How it works:
Enter your spool's inner diameter and width in the parameters for reference spool (you can do that in the Customizer app, link is on this page, or download OpenSCAD yourself). If this is your only spool size: set the second spool inner diameter to 0 so that no adapter is generated. In assembly view (output to "assembly") you can verify the arrangement if desired. Set output to "print" and export as STL. If slicing fails then fix the STL. Print the thing with your favourite material and print settings and test it out! The hub springs, which are printed vertically, are stabilized with small horizontal hub spring supports which should be cut away before assembling.
When loading filament, the spring must wind itself around the axle and not against the outer rim. If it is winding in the wrong direction, then the spring may break near the axle at high loads. Flipping the hub around will reverse the loading direction and solve this. The second picture shows the filament wound up in the correct way. Note that the filament is guided over top; if you use the small hole in the base instead then you have to flip the hub/spring around.
If you have two (or more) different spool sizes: enter the secondary spool diameter and width in the parameters to see if a suitable adapter can be generated; this should be the case if the diameter is at least 4 mm larger and/or the width is smaller than that of the primary spool.
If the generated hub is too wide for your existing spool stands: the spiral spring can be used as shaft by setting spring diameter to 0, which is then changed to the hub diameter. This should work for 45 mm (and bigger) spool sizes and result in 1-2 rewinding revolutions, like in the original auto-rewinder.
Hub width can also be reduced by setting hubFlushWithReferenceSpool="yes".
Another way to reduce hub width is to use a dummy primary spool with small width and small diameter and use your actual spools as secondary spool, generating adapters for each actual spool.
A smooth top face for the hub can be generated by setting hubSpringTopOffset to -3 (or more negative). This parameter is in the 'advanced parameters' section. Note that this setting makes the hub itself larger, as the hub spring blade lengths are determined by the reference spool width.
Axle with same length (120mm) as those provided with MMU2 is available for direct download, to fit certain existing spool holder systems.
- Axle slots are available for additional stability with a matching stand.
Axle stands and accessoires
Solid frame (70mm, 95mm and 113mm available; scale X for other sizes)
Filament Holder MMU2 (65mm and 95mm available; scale X for other sizes)
Frame and clips for Lack setup
Screw-down tabletop and wall mounted axle stands
MMU Under Shelf
Laser-cut Axle Stand
Wire shelving hanging holder
Rubbermaid container stand
MMU Spoolholder for IKEA Stuva / Besta
IKEA Samla BOX
Prusa i3 MK3 spool holder
- V1.11 Jan 13, 2019
- Added axleRotationStopAlignSize, axleRotationStopAlignThickness and axleRotationStopAlignOffset to match grooves in universal auto-rewinder stand
- V1.10 Jan 7, 2019
- Fixed hub spring dimensioning error when using hubSpringStart>1
- Bearing features now all disabled when bearingWidth=0
- V1.09 Jan 6, 2019
- Added parameters hubThreaded and hubThreadLength for universal auto-rewinder
- Fixed STL's after reports of slicing issues
- V1.08 Jan 4, 2019
- Added hubSpringSupportEnable and hubSpringSupportCount to stabilize hub springs during printing
- Split bearingDiameter into topBearingDiameter and bottomBearingDiameter
- Improved bottom bearing cavity shape for easier printing
- V1.07 Dec 8, 2018
- Changed default value of hubSpringTopOffset to -3 to make insertion of spools with internal cavities easier
- V1.06 Dec 7, 2018 with full credits to PeteThings
- Added slots in axle for more stability with matching stands
- Added parameters axleSlotPosition, axleSlotHeight, axleSlotWidth
- V1.05 Dec 6, 2018
- Fixed overlapping parts in print layout when specifying large axle diameter
- Added parameter useFlatSideInsert
- V1.04 Dec 5, 2018
- Fixed incorrect axle length calculation in case of wider 2nd spool
- Added parameter axleGrooveForSpacer
- Added parameter spacerClearance
- V1.03 Dec 5, 2018
- Added parameter hubSpringTopOffset
- Modified a couple of formulas for better consistency
- V1.02 Dec 2, 2018
- Changed default output to "print"
- Fixed bug in spring's axle mount height
- Calculation of hubSpringContactExtension capped to 3mm
- V1.01 Dec 2, 2018
- Added big stop block option
- Fixed incorrect error message
- Changed default hubSpringStart to 1 to avoid issues with clip gaps in certain configurations
- V1.0 Dec 1, 2018